Tassel seed mutations in maize. Maize plants bear two different types of inflorescences, the tassel and the ears. The tassel is branched and has made flowers, while the ears are unbranched and have female flowers. This occurs by formation of initially hermaphroditic flowers, followed by the selective abortion of male reproductive organs (stamens) in ear flowers and of female reproductive organs (pistils) in tassel flowers. the tassel seed mutations alter this pattern by allowing pistils to develop in flowers on the tassel seed mutations, such as Ts6 and ts4, also cause extra branches to form in the tassel (Ts6, left) and on the ear (Ts6, right; ts4, center).
Scanning electron micrograph of a young sunflower capitulum (left) and simulation of the same structure based on mechanical buckling of a thin circular plate (right). One family of spirals is highlighted in yellow.
Chimeric branches of the sawara false cypress, Chamaecyparis pisifera `nana aureovariegata' collected at Bernheim Forest, Clermont, Kentucky. Albino mutant sectors give rise irreversibly to completely albino branches, suggesting a single cell is the fount of all cells of a shoot.
DNA fragmentation characteristic of programmed cell death (PCD) was detected
in NaCl-treated determinate primary roots of Stenocereus gummosus (Cactaceae)
using the terminal deoxynucleotide transferase-mediated dUTP nick-end labeling
(TUNEL) assay. Nuclei in the bottom left image, a longitudinal section of a
root tip after PCD-inducing NaCl treatment, fluoresce blue after 4'-6-diamidino-2-phenylindole
(DAPI) staining. Those nuclei undergoing DNA fragmentation fluoresce green in
the same section (top left, fluorescein-isothiocyanate [FITC] staining). During
root development, PCD was not involved in meristem exhaustion, but did occur
in root-hair and root-cap cells. Both DNA and nuclear fragmentation were detected
in a root-hair cell (right: top, FITC; middle, DAPI). Dead remnants (red-fluorescing
nuclei, propidium-iodine stain, bottom right) of the root cap lie below a root
that has terminated growth.
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